This invention relates to a plugging device for a shaft furnace. More particularly, this invention relates to a compact plugging device for a shaft furnace having a wide pivoting angle. The plugging device of the present invention comprises a clay gun mounted on a jib and pivotable via a pair of hydraulic cylinders about a support column, such that when pivoted from an idle position to an operative position, a relatively low and comparatively flat continuous trajectory is swept out.
In a typical prior art plugging device, the means provided for pivoting the jib usually consists of hydraulic cylinders. These cylinders act to pivot a clay gun in accordance with the desired pivoting angle via a two part pivoting movement.
In the case where the desired pivoting angle does not exceed 120.degree. (or 130.degree. at the most), the hydraulic cylinder usually acts between a fixed point and a fulcrum on an arm or jib. While in theory, this above described structure would enable a pivoting angle to be reached of 180.degree., in practice, the mouth of the clay gun does not develop a sufficient contact pressure upon reaching the tap hole to be plugged. Therefore, in such a structure, the pivoting angle is usually limited to .+-.90.degree.. The above system offers the advantage of simple construction, however, the relatively small pivoting angle (.+-.90 degrees) prevents the clay gun from being withdrawn a desirable distance from the zone of the tap spout (in view of the high temperatures prevailing during the tapping the operation). Moreover, this system also creates a danger that the clay gun will constitute an encumbrance in its inoperative or idle position.
If a greater pivoting angle then as hereinabove described is required, a lever system may be provided, between a fixed point and a fulcrum on the jib, wherein a hydraulic cylinder will act to sweep out a wider i.e, larger, pivoting angle. This system permits pivoting angles of 180.degree. or more to be obtained, which are accompanied by a contact pressure between the mouth of the clay gun and the tap hole which is sufficiently great so as to properly function.
Typical embodiments of the two systems of shaft furnace plugging device, as described above are disclosed in German Pat. No. 21 57 712, corresponding to U.S. Pat No. 3,765,663, assigned to the assignee hereof, all of the contents of which are incorporated herein by reference.
While the shaft furnace plugging devices described in the above patent, are suitable for their intended purposes, there are nevertheless certain applications wherein the space occupied by the plugging device must be further reduced. In particular, there are certain circumstances wherein it has been found desirable to provide as much free space as possible between the pivotal drive of the clay gun and the shaft furnace. Alternatively, in other cases, it has been found desirable to provide a compact construction for the pivotal drive, so that it can be positioned closer to the shaft furnace during operation.